Oil sump

ABSTRACT

The present invention relates to an oil sump, wherein the oil sump comprises an upper and a lower thermoplastic part that each contains one or more ribs and wherein the upper and lower part are being joined such that at least one rib of the upper part is joined to at least one rib of the lower part.

The present invention relates to an oil sump, in particular an oil sumpof an internal combustion engine for driving a motor vehicle.

In order to reduce the weight of motor vehicles, oil sumps of plasticmaterials are increasingly used instead of metal oil sumps. WO 03/102387describes an oil pan comprising a shell of plastic material and asupport structure having perforations, wherein the shell is formed bymolding of plastic material onto said support structure, a portion ofthe plastic material extends through at least some of the perforationsof the support structure, the edges of said perforations being embeddedin the plastic material extending there through, thereby attachingfixedly the support structure to said shell. The support structureconsists of two separate parts.

A disadvantage of the oil pan as described in WO 03/102387 is that it,when the oil pan is in use, radiates noise to a high extent.

The aim of the present invention is to obtain an oil sump which islight-weight and radiates less noise when in use.

It has surprisingly been found that this aim can be achieved in that theoil sump comprises an upper and a lower thermoplastic part that eachcontains one or more ribs and wherein the upper and lower part are beingjoined such that at least one rib of the upper part is joined to atleast one rib of the lower part. With the oil sump according to theinvention, the stiffness of the oil sump can be increased without havingto increase the weight of the oil sump. It has been found that, comparedto a metal oil sump, the weight of the oil sump assembly can be reducedby more than 40%, but not at the expense of the performance of the oilsump.

An additional advantage of the oil sump according to the invention isthat a higher amount of oil can be stored at a given weight of the oilsump and/or at a given design space. Another advantage is that there isa more homogeneous stress distribution in the joined ribs and in thejoined wall resulting in that the critical loading on the oil sump canbe increased. As such, the oil sump is well able to carry the weight ofthe engine block so that the engine block can be placed directly onto afloor as this is generally done when the engine block is removed from amotor vehicle or before it is installed in a motor vehicle.

JP56057910U describes an oil sump containing, as a separate body fromsaid oil sump, a balance shaft installation block with an oil scatteringpreventing wall that has been constructed as one body with the balanceshaft installation block. The oil sump however does not contain an upperand a lower part which are joined such that at least one rib of theupper part is joined to at least one rib of the lower part.

For clarity purposes, in the oil sump according to the invention, theupper part is located on top of the lower part. As such, the totalvolume of the oil sump is larger than the volume of the upper part aswell as of the lower part.

The joining of the ribs is preferably effected by welding or gluing.Such welding or gluing is advantageous compared to mechanical joining inthat the homogeneous stress distribution in the joined ribs and in thejoined wall is even more pronounced. The joining of the ribs ispreferably effected by welding or gluing, more preferably by welding.More preferably, the welding is effected by laser welding, mirrorwelding or hot air welding.

Preferably, the upper and the lower thermoplastic part of the oil sumpare preferably further joined via their respective fixing surfaces. Thisjoining is preferably effected by welding or gluing, more preferably bywelding. More preferably, the welding is effected by laser welding,mirror welding or hot air welding. In a preferred embodiment, joiningthe ribs of the upper and lower thermoplastic part and joining therespective fixing surfaces of the upper and lower thermoplastic part iseffected in the same way and also in one operation. In a preferredembodiment, the total perimeter of the fixing surface of the upper partis smaller than the total perimeter of the fixing surface of the lowerpart; this results in an increase of the amount of oil that can bestored.

In a preferred embodiment, the oil sump consists of two thermoplasticparts, i.e. of the lower thermoplastic part and the upper thermoplasticpart.

It has surprisingly been found that with the oil sump according to thepresent invention it is possible to use an oil sump that issingle-walled, i.e. with only one plastic shell, while the strength ofthe oil sump is high enough. The use of a single-walled oil sump isadvantageous as this results in the need for less thermoplastic materialand thus in reduced weight compared to a double-walled thermoplastic oilsump. An additional advantage is that the manufacture of such oil sumpis very simple. The oil sump of the present invention is thereforepreferably single-walled.

Preferably, the oil sump contains interior ribs (ribs on the interiorsurface of the oil sump) and/or exterior ribs (ribs on the exteriorsurface of the oil sump). The ribs have the function of reinforcing theoil sump. More preferably, the oil sump contains interior ribs as wellas exterior ribs. Preferably, the oil sump contains interior ribs thatpreferably extend, when joined, over one of the longitudinal sides ofthe oil sump and more preferably also over the bottom of the lower partof the oil sump. The exterior ribs are preferably provided on the otherlongitudinal side of the oil sump. The exterior ribs preferably extend,when joined, over the entire longitudinal exterior side of the oil sump.Preferably, the interior ribs are not connected to the wall of thelongitudinal side of the oil sump on which the exterior ribs arepreferably provided. The latter results in that a complete drainage ofoil is possible. The oil sump preferably further contains domes in orderto be able to mechanically join the oil sump to an engine block. Such adome is preferably connected to a separate, interior bottom rib. As aresult of the presence of such interior ribs and exterior ribs, theradiation of noise is further reduced. In view of noise radiationreduction, the distance between the ribs is preferably at most 30 mm,more preferably at most 25 mm and even more preferably at most 20 mm;and the distance between the ribs is preferably at least 10 mm.

The oil sump is preferably produced from polyamide. The polyamide ispreferably polyamide 6 or polyamide 6,6 or a blend thereof. The oil sumpis preferably produced from reinforced polyamide. Reinforcing ispreferably effected by using glass fibres in a reinforcing amount, e.g.,in an amount of from 5 percent by weight to 60 percent by weight, basedon the total weight of the oil sump.

The oil sump of the present invention is in general a part of an oilsump assembly. Preferably, the oil sump assembly further contains (a) anengine block, (b) a gearbox or a coupling, and (c) a support bracketthat is attached to the gearbox or to the coupling and to the engineblock. Preferably, the bracket consists of one part. As used herein, onepart may also include different parts that are attached to each otherthereby forming one structural part. The use of such an oil sumpassembly results in that mechanical failure of the engine is reduced oreven prevented. An additional advantage of the use of such oil sumpassembly is that stresses in the plastic material of the oil sump arereduced or even prevented, resulting in less oil leakage and/or inreduced chance of failure of the thermoplastic oil sump.

Preferably, the support bracket has a Young's modulus higher than 20GPa, preferably higher than 22 GPa and more preferably higher than 25GPa. A Young's modulus higher than 20 GPa results in that deformation ofthe gearbox is lowered, resulting in less mechanical failure of theengine.

The support bracket is attached to the gearbox or the coupling and tothe engine block. Preferably, the support bracket surrounds a part ofthe oil sump. The oil sump is preferably attached to the support bracketprior to attaching the support bracket to the gearbox or to the couplingand to the engine block. This is advantageous as this results in easierassembling of the oil sump assembly. Preferably, the attaching iseffecting by assembling. The assembling is preferably effected usingscrews or more preferably using snaps. The latter is advantageous asusing snaps results in easier assembling and in that fewer parts areneeded for assembling.

The thermoplastic oil sump has the function of an oil reservoir and isat the same time a structural part of the oil sump assembly. An oil sumpis a reservoir for lubricating oil for an internal combustion engine fordriving a motor vehicle. Internal combustion engines are lubricated byoil which is pumped into bearings and thereafter allowed to drain to thebase of the engine. Oil is collected in an oil sump located at the baseof the engine and oil is redistributed from the oil sump duringoperation of the engine. The thermoplastic oil sump is adhered to theengine block. Preferably the adhesion is effected by sealing as thesealing results in less oil leakage and even in that the oil sumpassembly is tight for oil. Sealing can for example be effected by theuse of a seal ring and/or of a liquid seal. The use of a liquid seal ispreferred in view of the ease of assembling. The seal surface (of thethermoplastic material) of the oil sump preferably corresponds with oneor more of the seal surfaces of the engine block as this results in thatthe chance for oil leakage is further reduced. Preferably, the sealsurface of the oil sump is uninterrupted as this results in that thechance for oil leakage is further reduced.

The support bracket may be produced from a material selected from metal,thermoset plastic material, thermoplastic material and combinationsthereof. In a preferred embodiment, the support bracket is produced frommetal. Metal from which the support bracket may be produced include, butare not limited to, ferrous alloys, aluminum alloys and titanium alloys.Preferably, the support bracket consists of aluminum as the use ofaluminum is advantageous in view of weight and stiffness.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will be more apparentfrom the detailed description of one preferred embodiment of an oil sumpstructure according to the invention, which is described as anon-limiting example with the help of the accompanying drawings.

FIG. 1 and FIG. 2 are perspective views of an oil sump according to theinvention.

DETAILED DESCRIPTION OF THE INVENTION

The oil sump as shown in the figures consists of two thermoplasticparts, an upper part 1 and a lower part 2. The upper and lower part bothcontain interior ribs (3 a respectively 3 b) that are joined by means ofa weld 4 resulting in that the oil sump contains interior ribs whichextend over one of the longitudinal sides of the oil sump. The interiorribs 3 b further extend over the bottom of the lower part of the oilsump. The interior ribs 3 b and 8 are not connected to the wall of theother longitudinal side of the oil sump, resulting in an oil drain space11. The lower and upper part both contain exterior ribs (5 arespectively 5 b) that are joined by means of a weld 6 resulting in thatthe oil sump contains exterior ribs which extend over the otherlongitudinal side of the oil sump. The oil sump further contains domes 7in order to be able to mechanically join the oil sump to the engineblock. Such a dome is preferably connected with an interior bottom rib8. The bottom ribs 8, the interior ribs 3 a, 3 b and the exterior ribs 5a, 5 b may be molded on the surfaces of the oil sump separately from orconcurrently with the mold formation of the oil sump. Preferably, theribs 3 a, 3 b, 5 a, 5 b, 8 are molded on the surfaces of the oil sumpconcurrently with the mold formation of the oil sump. In FIG. 1, thethickness of the ribs is denoted as t, the height of the ribs is denotedas h and the length of the ribs is denoted as l. The oil sump isattached to a support bracket 9. The oil sump will be adhered to theengine block. The seal surface 10 of the oil sump preferably correspondswith one or more of the seal surfaces of the engine block.

1. An oil sump, wherein the oil sump comprises an upper thermoplasticpart (1) and a lower thermoplastic part (2) that each contains one ormore ribs (3 a, 3 b, 5 a, 5 b, 8) and wherein the upper and lower partare being joined such that at least one rib of the upper part is joinedto at least one rib of the lower part.
 2. An oil sump according to claim1, wherein the joining of the ribs is effected by welding or gluing. 3.An oil sump according to claim 1, wherein the oil sump is single-walled.4. An oil sump according to claim 1, wherein the oil sump contains ribson the interior surface (3 a, 3 b, 8) and ribs on the exterior surface(5 a, 5 b).
 5. An oil sump according to claim 4, wherein the interiorribs (3 a, 3 b), when joined, extend over one of the longitudinal sidesof the oil sump and over the bottom of the lower part of the oil sump.6. An oil sump according to claim 5, wherein the interior ribs (3 a, 3b) are not connected to the wall of the other longitudinal side of theoil sump
 7. An oil sump according to claim 4, wherein the exterior ribs(5 a, 5 b), when joined, extend over the other longitudinal side of theoil sump.
 8. An oil sump according to claim 1, wherein the upper and thelower thermoplastic part are welded or glued via their respective fixingsurfaces.
 9. An oil sump according to claim 8, wherein the welding iseffected by laser welding, mirror welding or hot air welding.
 10. An oilsump according to claim 1, wherein the oil sump consists of a reinforcedpolyamide.
 11. An oil sump according to claim 1, wherein thethermoplastic material is a glass fibre reinforced polyamide.
 12. An oilsump according to claim 10, wherein the polyamide is polyamide 6 orpolyamide 6,6 or a blend thereof.
 13. An oil sump according to claim 1,wherein the oil sump is a part of an oil sump assembly furthercontaining (a) an engine block, (b) a gearbox or a coupling, and (c) asupport bracket (9) that is attached to the gearbox or to the couplingand to the engine block.
 14. An oil sump according to claim 13, whereinthe bracket (9) consists of one part.